Investigating the biotic/abiotic reduction of Hg(II) under iron-reducing conditions

Mercury is a component of mixed wastes that have contaminated vast areas of the deep subsurface as a result of nuclear weapons and energy production. While ionic mercury is largely bound to sediment constituents, episodes of mercury mobilization in the form of Hg(0) can occur. Microbial processes that reduce Hg(II) to Hg(0) in anoxic groundwater aquifers may contribute to this problem. In collaboration of Prof. Tamar Barkay, we are investigating the biogeochemical reactions that control the reduction of Hg(II) under iron-reducing conditions. Specifically, we are testing the hypothesis that subsurface microorganisms can reduce Hg(II) by a coupled biotic/abiotic pathway mediated by the formation of reactive secondary Fe(II) phases.

Collaborator: Prof. Tamar Barkay

implications of biomineralization for contaminant sequestration.

The kinetics of ferrihydrite transformation catalyzed by reactive Fe^II. Synchrotron-radiation based ED-XRD is used to quantify the degree of reaction (α) as a function of time for the ferrihydrite to goethite conversion in the presence of Fe^II (Yee et al., 2006).